1. Field of the Invention
The present invention relates generally to telephone line protection devices, and more particularly to an improved telecommunications T1 carrier overvoltage protector and fiber to curb power protector.
2. Description of the Prior Art
Overvoltage protection devices are commonly used with telephone lines for protecting telephone equipment against hazardous power surges and transient voltages. Sources of transients include lightning, inductive switching electromagnetic interference (EMI), electrostatic discharge (ESD) and nuclear EMP (NEMP). Overvoltage protection circuitry that overcomes many disadvantages of the prior art circuitry is disclosed in McCartney, U.S. Pat. No. 4,758,920, issued Jul. 19, 1988 and McCartney et al., U.S. Pat. No. 4,941,063, issued Jul. 10, 1990 and both assigned to the assignee of the present invention.
A significant problem with known protection devices generally effective for overvoltage noise and transient protection is that, manual resetting is required with a typical holding current, such as greater than 260 milliamperes, present in the loop, because the typical overvoltage protector will remain in the low impedance mode, and as a result the overvoltage protector will be damaged or a fuse for the telephone system is blown.